Fix some static analysis defects.

A few silly errors, a few unlikely errors, a few changes that should
not have resulted in a problem but makes the code clearer.

Change-Id: Id2c82e9317d53822e4da13c94dec9595ea33b07a
Reviewed-by: Ling Hu <ling.hu@nokia.com>
Reviewed-by: Dmytro Poplavskiy <dmytro.poplavskiy@nokia.com>

src/plugins/gstreamer/mediacapture/qgstreamercapturesession.cpp

@@ -204,7 +204,6 @@ GstElement *QGstreamerCaptureSession::buildAudioSrc()
     if (m_audioInputFactory)
         audioSrc = m_audioInputFactory->buildElement();
     else {
-        audioSrc = gst_element_factory_make("pulsesrc", "audio_src");
         QString elementName = "alsasrc";
         QString device;